How to dynamical update the labels based on the array elements

Hi,

I have a array of lat long. I want to place a label in all the lat longs present in array.

For Example:

var source=[12,4,usa,13,5,uk];

var labels = scene.primitives.add(new Cesium.LabelCollection());
labels.add({
  position : new Cesium.Cartesian3.fromDegrees(source[0], source[1]),
  text : 'source[2]'
});
labels.add({
  position : new Cesium.Cartesian3.fromDegrees(source[3],source[4]),
  text : 'source[5]'
});

How to dynamical update the labels based on the array.

i tried the following code, it didn’t work

var len=source.length

for(var i=0;i<len;i++)

{

var n=(i+2);

viewer.entities.add({

position: Cesium.Cartesian3.fromDegrees(
source

[i], source

[i++]),

label: {

text: source

[n],

scale: 0.4,

fillColor: Cesium.Color.BLACK,

pixelOffset : new Cesium.Cartesian2(50, -25),

pixelOffsetScaleByDistance : new Cesium.NearFarScalar(1.0e3, 1.0, 1.5e6, 0.0)

}

});

}

}

I want to update labels on the map based on array elements.

Thanks and Regards

Vinay